Projection high-definition television (HDTV), high-resolution printing, and maskless semiconductor lithography are a few examples of applications of high-resolution optical display technology. In each case a one- or two-dimensional array of optical modulators and a companion optical system distribute light into millions of pixels that form an image. Some common types of optical modulators are digital mirror devices, grating light modulators, polarization light modulators, liquid crystals and liquid crystal on silicon panels. Depending on their design, these optical modulators may operate in reflective or transmissive modes.
MEMS ribbon structures are used in several types of optical modulators and, despite their simplicity, have spawned dozens of new designs for optical image forming systems. The evolution of optical ideas has led to systems that depend on fewer and fewer ribbons to create each pixel in the final image. Early grating light modulators used as many as six ribbons per pixel, for example, while polarization light modulators have been demonstrated with two ribbons per pixel.
MEMS ribbon structures most often appear in linear-array light modulators. Linear arrays “paint” two-dimensional images when their line-image output is swept back and forth by a scanner. Linear arrays take up far less chip real estate than two-dimensional arrays and are more closely matched to the etendue of laser light sources. If linear arrays could be made shorter by reducing the number of ribbons required to form a pixel, even more compact MEMS light modulator chips could be made.